Acer n35 serial port, the RS232 works!

Started by noname, Apr 01, 2006, 16:31

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noname

Hello, I'm a new user. I own an Acer n35 and I've found very useful the pinout diagram on this site.
I've built a serial cable for my Acer n35 and tested it with a RS232 peripheral. It works perfectly!
So it's possible to connect any serial (RS232) peripheral to this PDA!!
Bye

noname2

really ?

i try it with my n50 but i have no Tx signal ...
what com did u open (COM1?) ?
the signal is TTL (5V) or really RS232 (+-12V) ?
what pins did u connect , only TX-RX and GND, all, or did u connect some pin toguether (RTS-CTS for ex...) ?

thx for informations

Anonymous

can tell me where can I find out the mentioned pinout diagram? Thanks a lot!


Anonymous


noname

Quote from: "noname2"really ?

i try it with my n50 but i have no Tx signal ...
what com did u open (COM1?) ?
the signal is TTL (5V) or really RS232 (+-12V) ?
what pins did u connect , only TX-RX and GND, all, or did u connect some pin toguether (RTS-CTS for ex...) ?

thx for informations



I built a cable connecting all the 9 pins like the pinout on this site. However I use a peripheral that only needs 3: TR, RX and GND. I modified the small connector of the car charger (that has only the power pins), adding the serial pins.
I don't think the interface is TTL... I think it's a real rs232.
The serial port is the COM1, but I realized that:
*TO OPEN CORRECTLY THE COM PORT YOU MUST CONNECT THE CABLE TO THE POWER SUPPLY*
I think that this is because the rs232 and the charge circuit share the same GND....

Username

Quote from: "noname"
The serial port is the COM1, but I realized that:
*TO OPEN CORRECTLY THE COM PORT YOU MUST CONNECT THE CABLE TO THE POWER SUPPLY*
I think that this is because the rs232 and the charge circuit share the same GND....


I don't think it's so simple, because it can also work without the power supply.


When i read voltages outputs from the N35 port, i get 0V everywhere.

The com1 port seems to work only when a DCE (in my case, a RTC modem) is connected.

When i read voltage from the DCE disconnected, i get +9V or -9V (RS232 says it can go from +/-3V to up to +/-25V), and when connected, i can successfully talk to my modem using a pocket-pc TTY with some AT commands ...

When i read DCE outputs voltages while it is connected to my pocket-pc, i get approximatively +7V or -7V from the DCE, and about +6V to -6V from the N35.


I also tried to connect only 2 wires from the DCE to the N35 to see when it gives something else than 0V from one of its outputs, and i found that the N35 gives +6V or -6V only when a -7V output from the DCE is conencted to the N35 ... (and it does so, with or without the power supply)


My theories are :
1) the n35 com port "reuse" DCE outputs voltages to generate its own output signals.
2) the n35 is enabled only when it does detect a valid voltage from the DCE.


I'll have to do some more test to know which one is the good one ... :P

Username

(i post again, just to get notified :ninja:)

Username

Hello Again :ninja:

theory #2 is the good one :

The N35 activates its serial port only if the DCE gives a valid voltage on one of the input pins.


I applyed 5V on pin1 of the n35 serial port, and then, the pin4 goes from 0 to -5.64V when n35 is off, or +6.12V when n35 is on (edit : and that the COM1: port is being used by a software !).


So if you only need Rxd and Txd from the n35, you'll have to connect pin1 of the serial port to the +5V of 26pins port.

noname

Quote from: "Username"Hello Again :ninja:

theory #2 is the good one :

The N35 activates its serial port only if the DCE gives a valid voltage on one of the input pins.


I applyed 5V on pin1 of the n35 serial port, and then, the pin4 goes from 0 to -5.64V when n35 is off, or +6.12V when n35 is on (edit : and that the COM1: port is being used by a software !).


So if you only need Rxd and Txd from the n35, you'll have to connect pin1 of the serial port to the +5V of 26pins port.



Well, usually my n35 needs the external power just to open the COM1. After the com port is open I can disconnect the power supply and the serial comm still works good.
I've just looked at the peripheral that I use with the n35. In the circuit board there are only the RX, TX and GROUND signals. But I can see that the RTS and CTS pins of the connector are connected toghether at the end of the circuit.  :?:
Mistery...

I'll try your tip, thanks!

Username

Quote from: "noname"
I've just looked at the peripheral that I use with the n35. In the circuit board there are only the RX, TX and GROUND signals. But I can see that the RTS and CTS pins of the connector are connected toghether at the end of the circuit.  :?:
Mistery...


That must be a "loopback handshaking". You can do so on your N35 port.

Have a look at Google about "serial null modem".

percypoo

hi,can anyone help as the connector from inside my acer has come off the circuit board and i cannot charge unit,i only need to charge the unit as i only use the navigation part and dont need to link to pc.any help in what wires i can connect to inside unit to charge battery,many thanks percy.

Guestable

I too haver the same problem. Why don't you  make the RS232 and flog it to all those who have had the breakdown of the power connection. You'd make a fortune.

Anonymous

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